Source Compatibility: Mylyn 3.18 will not by be source compatible with previous versions.

Workspace Compatibility: We intend to keep Mylyn 3.18 upwards workspace-compatible with all versions higher than Mylyn 2.0 unless noted. This means that workspaces created with Mylyn 2.0 can be successfully opened by Mylyn 3.18 and upgraded to a 3.18 workspace.